7). 1/(√7-√11)
= 1×(√7+√11)/(√7-√11)(√7+√11)
= √7+√11 / (√7)² - (√11)²
= √7 + √11 / 7 - 11
= √7 + √11 / (-4)
EXPLAINATION:
to rationalize the denominator we multiply the numerator and the denominator by the denominator, but with the opposite sign.
For example - in the first question we multiplied 1 and √7 - √11 by √7 + √11 .
